In everyday life, we are faced with an increasing consumption of plastics, which often end up improperly disposed in the environment. When plastic is exposed to various environmental factors, it degrades into smaller fragments, known as microplastics. The widespread presence of microplastics in all types of ecosystems and the small size of the particles pose risks due to their impact on organisms and pose a challenge in particle monitoring. As a result, the number of studies in this field has also increased, focused on ecotoxicological impacts, adsorption properties, and the processes of aging and behaviour of particles in the environment. For this purpose, it is necessary to prepare environmentally relevant microplastics, which are produced with different fragmentation methods or with controlled polymerisation. Modified microplastics are increasingly being used in research, as their added properties make it easier to locate, track, and separate them from various studied systems, thereby potentially simplifying laboratory experiments. Several studies have already been conducted with microplastics doped with metals, fluorescent dyes, or magnetic particles. In this work, we focused on investigating the effects and potential applications of the latter. We used four different types of microplastics (polyethylene, polypropylene, polyvinyl chloride, and polyethylene terephthalate) coated with iron oxide nanoparticles. Toxicity tests showed that both unmodified and magnetically modified microplastics had no impact on Lemna minor (duckweed). Testing of iron leaching demonstrated that concentrations of leached iron in medium with neutral pH were negligible, confirming the stability of magnetic microplastics. We further examined the efficiency of separating these particles from water, sediments of two different grain sizes, and soils with two different moisture levels. Magnetic separation showed to be effective for removing particles from water and sediment (with recovery above 90 %), whereas the recovery of separation from soils was around 10 %.
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